Journal of Fungi

Article The (, ) from Based on Morphological and Molecular Data

Xin Meng 1,2,3, Geng-Shen Wang 1,2,3, Gang Wu 1,2, Pan-Meng Wang 1,2,3, Zhu L. Yang 1,2,* and Yan-Chun Li 1,2,*

1 Key Laboratory for Plant Diversity and Biogeography of East Asia, Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; [email protected] (X.M.); [email protected] (G.-S.W.); [email protected] (G.W.); [email protected] (P.-M.W.) 2 Key Laboratory for Fungal Diversity and Green Development, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China 3 College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China * Correspondence: [email protected] (Z.L.Y.); [email protected] (Y.-C.L.)

Abstract: Leccinum is one of the most important groups of . Most in this genus are ectomycorrhizal symbionts of various plants, and some of them are well-known edible , making it an exceptionally important group ecologically and economically. The scientific problems related to this genus include that the identification of species in this genus from China need to be verified, especially those referring to European or North American species, and knowledge of the phylogeny and diversity of the species from China is limited. In this study, we conducted multi- locus (nrLSU, tef1-α, rpb2) and single-locus (ITS) phylogenetic investigations and morphological   observisions of Leccinum from China, Europe and North America. Nine Leccinum species from China, including three new species, namely L. album, L. parascabrum and L. pseudoborneense, were revealed Citation: Meng, X.; Wang, G.-S.; Wu, and described. Leccinum album is morphologically characterized by the white basidioma, the white G.; Wang, P.-M.; Yang, Z.L.; Li, Y.-C. hymenophore staining indistinct greenish blue when injured, and the white context not changing The Genus Leccinum (Boletaceae, color in pileus but staining distinct greenish blue in the base of the when injured. Leccinum Boletales) from China Based on parascabrum is characterized by the initially reddish brown to chestnut-brown and then pale brownish Morphological and Molecular Data. J. Fungi 2021, 7, 732. https://doi.org/ to brown pileus, the white to pallid and then light brown hymenophore lacking color change when 10.3390/jof7090732 injured, and the white context lacking color change in pileus but staining greenish blue in the base of the stipe when injured. Leccinum pseudoborneense is characterized by the pale brown to dark brown Academic Editors: Anush Kosakyan, pileus, the initially white and then brown hymenophore lacking color change when injured, and Rodica Catana and Alona Biketova the white context in pileus and stipe lacking color change in pileus but staining blue in stipe when bruised. Color photos of fresh basidiomata, line drawings of microscopic features and detailed Received: 28 May 2021 descriptions of the new species are presented. Accepted: 31 August 2021 Published: 6 September 2021 Keywords: boletes; ; morphology; phylogeny; new taxa

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- 1. Introduction iations. The genus Leccinum Gray is a species-rich genus of Boletaceae and is characterized by a whitish or yellow hymenophore, a white to cream context unchanging or staining blue or red when injured, a brown to blackish scabrous to dotted squamules on the surface of the stipe, and comparatively long and smooth . Generally, most species Copyright: © 2021 by the authors. of the genus are widely spread in the subarctic, boreal, temperate and Mediterranean Licensee MDPI, Basel, Switzerland. regions, with a few secondary expansions to the neotropics [1–12]. Species in Leccinum This article is an open access article are both ecologically and economically important. Most species of this genus exhibit distributed under the terms and conditions of the Creative Commons mycorrhizal host specificity. Species of Leccinum sect. Scabra Smith & Thiers are associated Attribution (CC BY) license (https:// with plants of Betula, while species of L. sect. Fumosa (A.H. Smith, Thiers & Watling) Gelardi creativecommons.org/licenses/by/ are associated with plants of Populus. In L. sect. Leccinum, species are found exclusively 4.0/). associated with plants of Populus (e.g., L. albostipitatum den Bakker & Noordel. and L. insigne

J. Fungi 2021, 7, 732. https://doi.org/10.3390/jof7090732 https://www.mdpi.com/journal/jof J. Fungi 2021, 7, 732 2 of 18

A.H. Sm., Thiers & Watling), Betula (e.g., L. atrostipitatum A.H. Sm., Thiers & Watling), Pinaceae (e.g., L. vulpinum Watling and L. piceinum Pilát & Dermek) and Ericaceae that form arbutoidmycorrhizas (e.g., L. manzanitae Thiers and L. monticola Halling & G.M. Muell.). However, there are species in section Leccinum that are not host specific, i.e., L. aurantiacum (Bull.) Gray. This species is associated with plants of Betula, Populus, Quercus, Salix and sometimes with Tilia [13,14]. Some species of this genus are well-known edible mushrooms, such as L. quercinum (Pilát) E.E. Green & Watling, L. scabrum (Bull.) Gray and L. versipelle (Fr. & Hök) Snell, which are collected in China during the season. The genus Leccinum was established by Gray in 1821 [13], based on the type species L. aurantiacum. Subsequently, more and more mycologists noticed the morphological distinctness and described many new species of this genus. As currently circumscribed, the genus comprises roughly 150 species [1–3,6–56]. North America is the species diversity center of this genus, and in total 118 species have been recorded from this area [19]. Some of the most important works are the serial works of Smith and Thiers [1,15–17], in which three sections of this genus were proposed (L. sect. Leccinum Smith & Thiers, L. sect. Luteoscabra Smith & Thiers and L. sect. Scabra), with 68 species described from Michigan. Twelve species from Central America were described: one species from Belize, eight species from Costa Rica and three species from Colombia [20–24]. In Europe, Singer divided species of this genus into four sections, including two known sections, L. sect. Luteoscabra and L. sect. Leccinum, and two newly proposed sections, L. sect. Roseoscabra and L. sect. Eximia [3]. In Singer’s infrageneric classification, L. sect. Scabra, established by Smith and Thiers, was merged to L. sect. Leccinum. Recent molecular phylogenetic evidence has revealed that species of L. sect. Luteoscabra, L. sect. Roseoscabra and L. sect. Eximia belong to divergent of Boletaceae and represent many new genera (32,52–54). Thus, the genus Leccinum is restricted to the section Leccinum (Singer’s infrageneric classification) [3]. den Bakker and Noordelos revised the European Leccinum species based on morphology and nrLSU sequences and documented sixteen species [14]. In their subsequent study, they treated the three subclades revealed by den Bakker et al. in L. section Leccinum [33,57] as three subsections (viz. L. subsect. Leccinum, L. subsect. Fumosa A.H. Sm., Thiers & Watling and L. subsect. Scabra Pilat & Dermek) [14]. This infrageneric subdivision was followed in the treatment of the genus in this study. In the Southern Hemisphere, four species have been reported, including one from New Zealand and three from Australia [27–29]. In Asia, six species of Leccinum have been reported from [6]; ten species from Japan [7–10]; and a total of 31 species have been reported from China based on an extensive literature review [34–36,38–52,56]. Among these Chinese species, twelve species, viz. L. albellum (Peck) Singer, L. chromapes (Frost) Singer, L. crocipodium (Letell.) Watling, L. eximium (Peck) Singer, L. extremiorientale (Lar. N. Vassiljeva) Singer, L. griseum (Quél.) Singer, L. hortonii (A.H. Sm. & Thiers) Hongo & Nagas., L. nigrescens (Richon & Roze) Singer, L. rubropunctum (Peck) Singer, L. rubrum M. Zang, L. rugosiceps (Peck) Singer and L. subglabripes (Peck) Singer have been transferred to other genera [5,11,35,52–55]; eight species, viz. L. duriusculum (Schulzer ex Fr.) Singer, L. intusrubens (Corner) Høil., L. oxydabile (Singer) Singer, L. quercinum, L. rufum (Schaeff.) Kreisel, L. subleucophaeum E.A. Dick & Snell, L. subradicatum Hongo and L. variicolor Watling were reported without specimen support [39–43,49,51]; and eleven species, viz. L. ambiguum A.H. Sm. & Thiers, L. atrostipitatum A.H. Sm., Thiers & Watling, L. aurantiacum, L. holopus (Rostk.) Watling, L. olivaceopallidum A.H. Sm., Thiers & Watling, L. potteri A.H. Sm., Thiers & Watling, L. roseofractum Watling, L. scabrum, L. subgranulosum A.H. Sm. & Thiers, L. subleucophaeum var. minimum C.S. Bi and L. versipelle were reported with specimen citations [34,38,44–48]. Among these eleven species reported with specimen citations, only L. subleucophaeum var. minimum was originally described from China, and the remaining species were identified as species originally described from Europe and North America based on general morphological similarities. Indeed, a few species described from Europe and North America do occur in China, especially in northeastern and northwestern China. However, J. Fungi 2021, 7, 732 3 of 18

most species found in China have evolved independently in the southern part of China. Thus, identification of the Chinese Leccinum species needs to be reconfirmed. In this study, we used both morphological data and molecular sequences from the nu- clear ribosomal internal transcribed spacer (ITS), the large subunit of the nuclear ribosomal RNA (nrLSU), the translation elongation factor 1-alpha (tef1-α) and the RNA polymerase II second largest subunit (rpb2), together with ecological data to (1) elucidate species diversity of Leccinum in China; (2) evaluate the phylogenetic relationships of species within Leccinum; (3) make morphological and ecological comparisons between closely related species.

2. Materials and Methods 2.1. Taxon Sampling Nineteen specimens of the genus Leccinum from China were examined. For each collection, a part of the basidioma was dried with silica gel for DNA extraction. The remaining materials were then air-dried at 45–50 ◦C using an electric food dehydrator. Specimens studied in this work were deposited in the Herbarium of the Kunming Institute of Botany, Chinese Academy of Sciences (KUN). Genera are abbreviated as follows: L. for Leccinum, Le. for Leccinellum, O. for Octaviania, R. for Rossbeevera, Ru. for Rugiboletus, T. for Turmalinea, Ca. for Castanopsis, Li. for Lithocarpus, P. for Pinus and Q. for Quercus.

2.2. Morphological Observation The macroscopic descriptions are based on the detailed field notes and photographs of fresh basidiomata. Color codes of the form “4B2” indicate the plate, row, and color block from Kornerup and Wanscher [58]. For microscopic studies, the microscopic features of each part of the basidioma were observed under microscope (Leica DM2000, Leica Microsystems, Wetzlar, Germany), including basidiospores, basidia, cheilocystidia, pleurocystidia and pileipellis, using 5% KOH as a mounting medium to revive the dried materials. Microscopic studies follow Zhou et al. [59]. In the description of Basidiospores, the abbreviation n/m/p means n basidiospores measured from m basidomata of p collections in 5% KOH solution. The notation of the form (a) b–c (d) stands for the dimensions of the basidiospores; the range b–c contains a minimum of 90% of the measured values, a or d given in parentheses stands for extreme values. Q is used to mean “length/width ratio” of a in a side view; Qm means average Q of all basidiospores ± sample standard deviation. Measurements of basidospores, cystidia, basidia and terminal cells in pileipellis are presented as length × width. All microscopic structures were drawn freehand from rehydrated material under the microscope with 10× eyepiece and 100× objective (the total magnification is 1000×).

2.3. Molecular Procedures Genomic DNA was extracted from silica gel dried materials or herbarium specimens using the CTAB (Cetyltrimethyl ammonium bromide) method [60]. Polymerase chain reactions (PCRs) were performed to amplify partial sequences of nrLSU, tef1-α, rpb2 and ITS using the extracted DNA. The nrLSU region was amplified with primers LROR/LR5 and LROR/LR3 [61]; tef1-α was amplified with primer pair EF1-983F and EF1-1567R [62]; rpb2 was amplified with primers bRPB2-6F and bRPB2-7.1R [63] and ITS was amplified with primer pair ITS1 and ITS4 [64]. Protocols for the polymerase chain reactions (PCRs) and sequencing followed those in Wu et al. [65] and the references therein.

2.4. Sequence Alignments and Phylogenetic Analyses The newly generated sequences of each locus were blasted in GenBank, and the most closely related sequences (nucleotide identities >95%) were downloaded for further alignment. Sequences were aligned separately for each of the loci using MAFFT v7.130b with the E-INS-I strategy and manually optimized on BioEdit v7.0.9 [66,67]. Two datasets, the ITS dataset and the multi-locus (nrLSU + tef1-α + rpb2) dataset, were analyzed using RAxML and Bayesian methods, respectively. For the multi-locus dataset, single-gene analyses were conducted to assess incongruence among individual genes using the ML J. Fungi 2021, 7, 732 4 of 18

method (results not shown). Because no well-supported bootstrap value (BS > 70%) [55] conflict was detected among the topologies of the three genes, their sequences were then concatenated together for further multi-locus analyses. For ML analyses, the multi-locus and ITS datasets were analyzed using RAxML (https://www.phylo.org/, accessed on 26 August 2021) under the model GTRGAMMA [68]. Statistical supports for the phylogenetic analyses were determined using nonparametric bootstrapping with 1000 replicates. For BI analyses, the parameter model was selected by the Akaike information criterion (AIC) as the best-fit likelihood model with Modeltest 3.7 (Free Software Foundation, Boston, MA, USA) [69]. The models employed for each of the four loci were GTR + I + G for ITS, nrLSU and tef1-α, and SYM + I + G for rpb2. Posterior probabilities (PP) were determined twice by running one cold and three heated chains in parallel mode, saving trees every 1000th generation. Other parameters were kept at their default settings. Runs were terminated once the average standard deviation of split frequencies went below 0.01 [70]. Chain convergence was determined using Tracer v1.5 (http://tree.bio.ed.ac.uk/software/tracer/, accessed on 26 August 2021) to confirm sufficiently large ESS values (>200). Subsequently, the sampled trees were summarized after omitting the first 25% of trees as burn-in using the ‘sump’ and ‘sumt’ commands implemented in MrBayes.

3. Results 3.1. Molecular Phylogenetic Analysis A total of 57 sequences, including fifteen for nrLSU, fifteen for tef1-α, fourteen for rpb2 and thirteen for ITS, were newly generated in this study and aligned with sequences downloaded from GenBank. Sequences retrieved from GenBank and obtained in this study for the multi-locus phylogenetic analyses are listed in Table1. The multi-locus dataset (Supplementary File S1) contained 122 sequences (49 for nrLSU, 41 for tef1-α, 32 for rpb2), representing 51 samples, and the alignment contained 2195 nucleotide sites, of which 530 were parsimony informative. Borofutus dhakanus Hosen & Zhu L. Yang and Spongiforma thailandica Desjardin, Manfr. Binder, Roekring & Flegel were chosen as the outgroup [71,72]. ML and Bayesian analyses produced very similar estimates of tree topologies, and thus only the tree inferred from ML analysis is displayed (Figure1). The monophyly of Leccinum was highly supported (BS = 100% and PP = 1) in our analyses. Four main clades were recovered, and three of them correspond to the three known subsections, viz. L. subsect. Leccinum, L. subsect. Fumosa and L. subsect. Scabra of L. sect. Leccinum [14]. Three new species, namely L. album, L. parascabrum and L. pseudoborneense, were revealed in our multi-locus phylogenetic analyses. Leccinum parascabrum formed the remaining with BS = 100% and PP = 1, while L. pseudoborneense and L. album nested in L. subsect. Scabra and clustered together with L. flavostipitatum E.A. Dick & Snell, L. subradicatum and L. variicolor with low supported lineage (BS = 54%).

Table 1. Information on specimens used in multi-locus phylogenetic analyses and their GenBank accession numbers. Sequences newly generated in this study are indicated in bold.

GenBank Number Species Voucher Locality Reference ITS nrLSU tef1-α rpb2 Leccinellum corsicum Buf 4507 USA - KF030347 KF030435 - [55] Le. crocipodium MICH:KUO-07050707 USA - MK601749 MK721103 MK766311 [5] Le. aff. griseum KPM-NC-0017381 Japan - JN378508 JN378449 - [73] Le. lepidum K(M)-142974 Italy - MK601751 MK721105 MK766312 [5] Le. pseudoscabrum CFMR:DPL-11432 USA - MK601752 MK721106 MK766313 [5] Le. rugosiceps CFMR:BOS-866 USA - MK601770 MK721124 MK766329 [5] MZ392872 MW413907 MW439267 MW439259 Leccinum album KUN-HKAS53417 China This study MZ392873 HQ326880 HQ326861 MW439260 L. aurantiacum L-0342207 France - MK601759 MK721113 MK766318 [5] L. cerinum MK11800 Finland - AF139692 - - [4] L. duriusculum KUN-HKAS101160 Uzbekistan MZ485402 MZ675541 MZ707785 MZ707779 This study L. duriusculum GL4676 France - AF139699 - - [4] J. Fungi 2021, 7, 732 5 of 18

Table 1. Cont.

GenBank Number Species Voucher Locality Reference ITS nrLSU tef1-α rpb2 L. flavostipitatum MENMB10801 USA - MH620342 - - GenBank L. holopus MICH:KUO09150707 USA - MK601763 MK721117 MK766322 [5] L. holopus 9109303 France - AF139700 [4] L. holopus KUN-HKAS111906 Austria - MW413906 MW439266 MW439258 This study L. manzanitae NY-14041 USA - MK601765 MK721119 MK766324 [5] L. melaneum KUN-HKAS57220 China MZ485409 MZ675542 MZ707786 MZ707780 This study L. monticola NY-00815448 Costa Rica - MK601767 MK721121 MK766326 [5] L. monticola NY-760388 Costa Rica - MK601766 MK721120 MK766325 [5] L. palustre MK11107 Germany - AF139701 - - [4] “L. palustre” hdb030 Netherlands AF454586 - - - [57] L. parascabrum KUN-HKAS99903 China MZ392874 MW413911 MW439271 MW439264 This study L. parascabrum KUN-HKAS59447 China MZ392875 MW413912 MW439272 MW439265 This study L. pseudoborneense KUN-HKAS110156 China MZ412902 MW413908 MW439268 MW439261 This study L. pseudoborneense KUN-HKAS110157 China MZ412903 MW413909 MW439269 MW439262 This study L. pseudoborneense KUN-HKAS110158 China MZ412904 MW413910 MW439270 MW439263 This study L. pseudoborneense KUN-HKAS89139 China - MZ536631 MZ543306 MZ543308 This study L. pseudoborneense KUN-HKAS92401 China - MZ536632 MZ543307 MZ543309 This study L. quercinum KUN-HKAS63502 China - KF112724 KF112250 KF112724 [65] L. quercinum Lq1 Germany - DQ534612 - - [74] “L. scabrum” KUN-HKAS56371 China - KT990587 KT990782 KT990423 [11] L. scabrum KUN-HKAS57266 China - KF112442 KF112248 KF112722 [65] L. scabrum KUN-HKAS98029 China MZ485407 MZ675543 MZ707787 - This study L. scabrum KPM-NC-0017840 UK - JN378515 JN378455 - [73] L. schistophilum KUN-HKAS98024 China MZ503508 MZ675544 MZ707788 - This study L. schistophilum VDKO1128 Belgium - - KT824055 KT824022 [75] L. subradicatum KPM-NC-24518 Japan MT934814 MT812736 MT874822 - [76] L. sp. KPM-NC-0017830 Japan KC552009 [77] L. variicolor Lvar1 Germany - AF139706 - - [4] L. variicolor Hdb327 Canada AY538843 - - - [33] L. variicolor Watling6753 UK AY853538 - - - [78] L. versipelle KUN-HKAS76669 China - KF112443 KF112249 KF112723 [65] L. versipelle CFMR DLC2002-122 USA - MK601778 - - [5] L. versipelle - Sweden AF454573 - - - [57] L. versipelle KUN-HKAS97997 China MZ485404 MZ675545 MZ707789 MZ707781 This study L. versipelle KUN-HKAS99380 China MZ485401 MZ675546 MZ707790 MZ707782 This study L. violaceotinctum CFMR:BZ-1676 Belize - MK601780 MK721133 MK766337 [5] L. violaceotinctum CFMR:BZ-3169 Belize - - MK721134 MK766338 [5] Borofutus dhakanus KUN-HKAS73789 Bengal - JQ928616 JQ928576 JQ928597 [72] Chamonixia DBG:F023359 USA - MK601728 MK721082 MK766290 [5] brevicolumna Octaviania KPM-NC-0017812 Japan - JN378486 JN378428 - [73] japonimontana O. tasmanica NY-02449788 USA - MK601798 MK721152 MK766355 [5] Rossbeevera GDGM45913 China - MH537793 - - [79] griseobrunnea R. eucyanea KPM-NC-0023895 Japan - KP222896 KP222915 - [76] Rugiboletus andinus NY-00796145 USA - MK601758 MK721112 MK766317 [5] Ru. andinus NY-181460 USA - MK601757 MK721111 MK766316 [5] Spongiforma DED7873 Thailand - NG_042464 KF030436 MG212648 [71] thailandica Turmalinea KPM-NC-0017743 Japan - KC552050 - - [77] mesomorpha T. yuwanensis KPM-NC0023377 Japan - KJ001098 KJ001083 - [77] Tylocinum griseolum KUN-HKAS52612 China - KT990631 KT990825 - [11] J. Fungi 2021, 7, 732 6 of 18

Figure 1. Maximum-likelihood phylogenetic tree generated from a three-locus (nrLSU + tef1-α + rpb2) dataset. BS > 50% in ML analysis and PP > 0.95 in Bayesian analysis are indicated as RAxML BS/PP above or below supported branches. Species of this genus from China and type species of this genus (L. aurantiacum) are indicated in bold. Voucher specimens and localities where the specimens were collected are provided behind the species names. AU = Austria, BE = Belgium, CN = China, CR = Costa Rica, FI = Finland, FR = France, GER = Germany, IT = Italy, JP = Japan, TAI = Thailand, UK =United Kingdom, USA = United States of America and UZ = Uzbekistan.

For the ITS dataset, as revealed by den Bakker et al. [57] and our primary analysis, the ITS1 region contains a minisatellite, which is characterized by the repeated presence of CTATTGAAAAG and CTAATAGAAAG core sequences and mutational derivatives. Moreover, some species contain a minisatellite in the ITS2 region, e.g., the newly described species L. album (GenBank Acc. No.: MZ392872 for clone 1 and MZ392873 for clone 2), with a region of 212 bp that consists of tandem repeats (see Supplementary Material for details). Though there is length variation in either the ITS1 or ITS2 spacers, it can also provide some phylogenetic signals. We performed phylogenetic analyses of the ITS dataset. In this dataset (Supplementary File S2), 51 samples were included. The length of the dataset was 1416 bp, of which 377 were parsimony informative. Leccinellum albellum (Peck) Bresinsky & Manfr. Binder was chosen as outgroup. ML and Bayesian analyses also produced very similar estimates of tree topologies, and only the tree inferred from ML analysis is displayed (Figure2). The monophyly of Leccinum was also well supported (BS = 100% and PP = 1) in our analyses. Three new species viz. L. album, L. parascabrum and L. pseudoborneense) were revealed. Leccinum album is closely related to L. pseudoborneense yet without statistical support, while L. parascabrum forms an independent lineage. Species to which L. parascabrum is phylogenetically related remain as yet unknown. J. Fungi 2021, 7, 732 7 of 18

Figure 2. Maximum-likelihood phylogenetic tree generated from ITS dataset. BS > 50% in ML analysis is indicated above or below supported branches. Species of this genus from China and type species of this genus (L. aurantiacum) are indicated in bold. Voucher specimens, localities and GenBank numbers are provided behind the species names. AT = Austria, CAN = Canada, CN = China, CR = Costa Rica, FR = France, GL = Greenland, JP = Japan, NL = The Netherlands, PL = Poland, SW = Sweden, UK =United Kingdom, USA = United States of America and UZ = Uzbekistan.

Our ML and Bayesian analyses of ITS and multi-locus datasets revealed the existence of eight Leccinum species from China, including five known species viz. L. melaneum (Smotl.) Pilát & Dermek, L. quercinum, L. scabrum, L. schistophilum and L. versipelle and three new species viz. L. album, L. parascabrum, and L. pseudoborneense. The final alignments of both datasets were deposited in TreeBASE (S27490).

3.2. Taxonomy Leccinum album X. Meng, Yan C. Li & Zhu L. Yang, sp. nov., (Figures3g–h and4). MycoBank: MB 838917. Diagnosis: This species differs from other species in Leccinum in the combination of the entirely white pileus, the white pileal context not changing color when injured, the white hymenophore staining indistinct greenish blue when hurt, the white stipe coarsely covered with initially white and then darkened verrucose squamules, and the white stipe context always staining greenish blue at the base when injured. Holotype: CHINA. Hunan Province: Chenzhou, Zhanghua County, Mangshan Na- tional Forest Park, E 112◦920, N 24◦940, alt. 850 m, associated with Castanopsis fissa, Cyclobal- anopsis glauca, Lithocarpus glabra and Pinus kwangtungensis, 3 September 2007, Y.C. Li1072 (KUN-HKAS53417, GenBank Acc. No.: MZ392872 and MZ392873 for ITS, MW413907 and HQ326880 for nrLSU, MW439267 and HQ326861 for tef1-α, and MW439259 and MW439260 for rpb2). J. Fungi 2021, 7, 732 8 of 18

Figure 3. Basidiomata of Leccinum species. (a–c) Leccinum parascabrum (KUN-HKAS99903, holotype); (d–f) Leccinum pseudoborneense ((d) from KUN-HKAS110157; (e,f) from KUN-HKAS110156, holotype); (g,h) Leccinum album (KUN-HKAS53417, holotype).

Etymology: Latin “album” means white, referring to the color of the basidiomata. Basidiomata small to medium-sized. Pileus 3–5.5 cm in diam., hemispherical when young, subhemispherical to convex or plano-convex when mature, white (1A1) when young, white to cream (2B2–3) when mature; surface covered with concolorous farinose to pubescent squamules; context 5–10 mm thick in the center of pileus, taste mild, white (1A1) to pallid, not changing color when bruised; Hymenophore adnate when young, adnate to slightly depressed around apex of stipe; surface white (1A1), staining indistinct greenish blue (25B5–7) when injured; pores subangular to roundish, 0.3–1.5 mm wide; tubes up to 5 mm long, white to dirty pinkish (13A2), not changing color when bruised. Stipe 8–10 × 0.8–1.2 cm, clavate to subcylindrical, always enlarged downwards; surface white (1A1), densely covered with white (1A1) verrucose squamules, staining light greenish blue at base when injured; context whitish (1A1), staining blue at base when injured; basal mycelium white (1A1), lacking color change when injured. J. Fungi 2021, 7, 732 9 of 18

Figure 4. Microscopic features of Leccinum album (KUN-HKAS53417, holotype). (a) Basidiospores. (b) Basidia and pleurocystidium. (c) Cheilocystidia and pleurocystidia. (d) Pileipellis. Bars = 10 µm. Drawings by Y.-C. Li.

Basidiospores (40/2/1) 15–19 × 5–7 µm, Q = 2.5–3, Qm = 2.75 ± 0.15, subfusiform to narrowly ellipsoid in side view with slight suprahilar depression, subcylindrical to fusiform in ventral view, smooth, somewhat slightly thick-walled (up to 0.5 µm thick), hyaline to yellowish in KOH, brownish yellow to olivaceous brown in Melzer’s Reagent. Basidia 23–33 × 10–13 µm, clavate, 4-spored, hyaline to yellowish in KOH, yellowish to brownish yellow in Melzer’s Reagent. Hymenophoral trama boletoid, hyphae subcylindri- cal, 4–10 µm wide, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s Reagent. Cheilo- and pleurocystidia 42–60 × 11–17.5 µm, abundant, subfusiform to fusiform, thin- walled, yellowish in KOH, yellowish to brownish yellow in Melzer’s Reagent. Pileipellis a trichoderm, composed of more or less vertically arranged 5–10 µm wide hyphae, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s Reagent. Pileal trama made up of 6–12 µm wide filamentous hyphae, thin-walled, yellowish in KOH, yellowish to brownish yellow in Melzer’s Reagent. Clamp connections absent in all tissues. Habitat and distribution: Solitary or scattered in tropical forests dominated by plants of the families (Castanopsis fissa, Cyclobalanopsis glauca and Lithocarpus glabra) and Pinaceae (Pinus kwangtungensis or P. armandii); on acidic, humid and loamy soils; J. Fungi 2021, 7, 732 10 of 18

distribution insufficiently known, rather rare in China and currently found in central and southeastern China (Hunan and Fujian Provinces). Additional Specimen examined: CHINA. Fujian Province: Jianning County, E 116◦840, N 26◦830, alt. 900 m, associated with Castanopsis fissa, Cyclobalanopsis glauca and Pinus armandii, 16 July 1971, N.L. Huang 716 (KUN-HKAS39522). Commentary: Leccinum album is characterized by the white pileus, the white hy- menophore staining indistinct greenish blue when hurt, the white stipe densely covered with initially white and then darkened scabrous squamules, the white context in pileus not changing color when injured, and the white context in stipe unchanging or only staining distinct greenish blue at base when injured. Morphologically, L. album is close to L. holopus, L. cyaneobasileucum Lannoy & Estadès and Le. albellum (Peck) Bresinsky & Manfr. Binder in similar pileus colors. However, L. holopus, originally described from Europe (Germany), differs from L. album in its medium to large basidiomata (pileus 4–10 cm wide), becoming more viscid pileus with age, pure white or dirty white to pale buff or pale pallid pileus always with a glaucous green tinge, long hymenophoral tubes measuring 9–15 mm long, narrow and subcylindrical hymenial cystidia measuring 30–50 × 7.5–12.5 µm, narrow pileipellis hyphae measuring 3.5–5 µm wide, and association with trees of the genus Be- tula (Betulaceae) [80–82]. Leccinum cyaneobasileucum, originally described from France, is different from L. album in its white or greyish brown to light brown pielus, woolly stipe surface, slender basidiospores with Qm ≥ 3, relatively narrow hymenial cystidia measuring 32–44 × 5.5–7.5 µm, narrow pileipellis hyphae measuring 2–6.5 µm wide, and association with trees of the genus Betula [83]. Leccinellum albellum, originally described from New York, is characterized by its basidiomata not changing color when bruised and narrow basidiospores measuring 13–20 × 4–6 µm [16,17,30]. Phylogenetically, L. album is related to L. variicolor and L. pseudoborneense in the analyses of the multi-locus and ITS datasets, respectively (Figures1 and2). However, L. variicolor differs from L. album in its white to grey or cream pileal context staining vinaceous to brown when bruised, white stipe context staining pink to coral red in the upper part and green- blue in the lower part when bruised and association with plants of Betula [81]. Leccinum pseudoborneense is different from L. album in its pale brown to dark brown pileus, white context in pileus and stipe staining blue when bruised, narrow basidiospores measuring (11) 12–19 (20) × 4–5 (6) µm, narrow hymenial cystidia measuring 28–40 × 4–10 µm, and distribution in southwestern China. Leccinum parascabrum X. Meng & Yan C. Li & Zhu L. Yang, sp. nov., (Figures3a–c and5 ). MycoBank: MB 838916. Diagnosis: This species differs from other species in Leccinum by its initially reddish brown to chestnut-brown and then brown to pale brownish or even dirty white pileus, white pileal context lacking color change when injured, white to pallid and then light brown hymenophore lacking color change when injured, and the white stipe context staining greenish blue at the base when injured. Holotype: CHINA. Hunan Province: Chenzhou, Zhanghua County, Mangshan Na- tional Forest Park, E 112◦920, N 24◦940, alt. 1100 m, associated with Castanopsis fissa, Litho- carpus glabra and Pinus kwangtudgensis, 12 September 2016, G. Wu 1784 (KUN-HKAS99903, GenBank Acc. No.: MZ392874 for ITS, MW413911 for nrLSU, MW439271 for tef1-α, and MW439264 for rpb2). Etymology: Latin “parascabrum” refers to its similarity to L. scabrum. Basidiomata small to medium-sized. Pileus 2.5–12.5 cm in diam., hemispherical when young, subhemispherical to convex or applanate when mature, reddish brown (12E8) to chestnut-brown (8C7–8) when young, brown (6C6) to pale brownish (7D7–8) or even dirty white (6A2) when mature; surface tomentose; context 6–13 mm thick in the center, white (1A1), not changing color when bruised; Hymenophore adnate when young, adnate to slightly depressed around apex of stipe; surface white to pallid (1A1) when young, and becoming light brown (6B4) when mature, not changing color when injured; tubes 6–14 mm long, 0.5–1.5 mm wide, creamy white (1A1), not changing color when bruised. J. Fungi 2021, 7, 732 11 of 18

Stipe 12–14 × 1.1–2.2 cm, clavate, swollen downwards, always staining greenish blue at base when injured; surface white (1A1), covered with initially white (1A1) to light beige (5A4) and then brownish (7D8) squamules; context white (1A1), staining greenish blue (25B6–7) at base when injured; basal mycelium white (1A1).

Figure 5. Microscopic features of Leccinum parascabrum (KUN-HKAS99903, holotype). (a) Basid- iospores. (b) Basidia and pleurocystidium. (c) Cheilocystidia. (d) Pleurocystidia. (e) Pileipellis. Bars = 10 µm. Drawings by Y.-C. Li.

Basidiospores (80/2/2) 16–20 (–21) × 5–6 µm, Q = 3.2–3.8, Qm = 3.43 ± 0.18, sub- fusiform to fusiform, slightly thick-walled (up to 0.5 µm thick), yellowish to yellowish brown in KOH, yellow to yellow-brown in Melzer’s Reagent. Basidia 24–33 × 8–12 µm, clavate, 4-spored, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s Reagent. Hymenophoral trama boletoid, hyphae cylindrical, 3–7 µm wide, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s Reagent. Cheilo- and pleurocystidia 34–68 × 7.5–16 µm, abundant, subfusiform to fusiform, thin-walled, yellowish to pale yellowish brown in KOH, yellowish brown to brown in Melzer’s Reagent. Pileipellis a trichoderm, composed of 5–9 µm wide filamentous hyphae, yellowish to pale brownish in KOH. Pileal trama made J. Fungi 2021, 7, 732 12 of 18

up of 5–10 µm wide filamentous hyphae, thin-walled, hyaline to yellowish in KOH, yel- lowish to brownish yellow in Melzer’s Reagent. Clamp connections absent in all tissues. Habitat and distribution: Solitary or scattered in tropical forests dominated by plants of the families Fagaceae (Lithocarpus glabra, Castanopsis fissa and Ca. hystrix) and Pinaceae (Pinus kwangtudgensis or P. yunnanensis.); on acidic or slightly alkaline, loamy soils; dis- tribution insufficiently known, rather rare in China, currently known from central and southwestern China (Hunan and Yunnan Provinces). Additional Specimen examined: CHINA. Yunnan Province: on the way from County to Longling County, E 98◦590, N 24◦810, alt. 2010 m, associated with Lithocar- pus glabra, Castanopsis hystrix and Pinus yunnanensis, 19 July 2009, Y.C. Li 1700 (KUN- HKAS59447, GenBank Acc. No.: MZ392875 for ITS, MW413912 for nrLSU, MW439272 for tef1-α, and MW439265 for rpb2). Commentary: Leccinum parascabrum is characterized by the initially reddish brown to chestnut-brown and later brown to pale brownish or even dirty white pileus, the white pileal context not changing color when injured, the white to pallid and then light brown hymenophore not changing color when injured, the white stipe context with greenish blue color change at the base when injured, and the relatively large basidiospores measur- ing 16–20 (–21) × 5–6 µm, Q = 3.2–3.8. Leccinum parascabrum generally shares the similar colors of pileus and hymenophore, and the similar slender stems with L. duriusculum, L. griseonigrum A.H. Sm., Thiers & Watling, L. scabrum, L. uliginosum A.H. Sm. & Thiers and Le. pseudoscabrum (Kallenb.) Mikšík. However, L. duriusculum, originally described from Europe, can be distinguished from L. parascabrum by its pale grey-brown to dark greyish or reddish brown pileus, white context staining violaceous pink when bruised but yellow-green to blue-green in the base of stipe, relatively small basidiospores mea- suring 11.5–15.5 × 4.5–6 µm [84]. Leccinum griseonigrum, originally described from North America, differs from L. parascabrum in its avellaneous to dingy cinnamon-buff pileus, white pileal context staining blue when bruised, relatively small basidiospores measuring 13–16 × 4–5.5 µm, and association with trees of the genus Populus [16]. Leccinum scabrum differs from L. parascabrum in its wrinkled pileus, pale white hymenophore, pinkish dis- coloration when injured, and never bluish color change at the base of stipe [13,14,81]. Leccinum uliginosum, originally described from North America, is different from L. paras- cabrum in its dark fuscous to drab-grey pileus, white context in pileus becoming reddish and then fuscous when bruised, relatively small basidiospores measuring 14–18 × 3.5–5 µm, and small and inconspicuous hymenial cystidia [17]. Leccinellum pseudoscabrum differs from L. parascabrum in its initially red to purplish brown and then blackish brown context color change when injured, and the palisadoderm pileipellis composed of subglobose cells [14]. Leccinum parascabrum also shares the similar colors of pileus and hymenophore and the bluish color change at the base of stipe with L. variicolor. However, L. varii- color is different from L. parascabrum in its white to grey or cream pileal context staining vinaceous to brown when bruised, white stipe context staining pink to coral red in the upper part and green-blue in the lower part when bruised, relatively small basidiospores measuring (10) 13.5–17.5 (–20.0) × 5.0–6.5 (7.0) µm with Q = 2.4–3.1, and association with plants of Betula sp. [81]. In our phylogenetic analysis of the multi-locus and ITS datasets (Figures1 and2 ), L. parascabrum formed independent clades within Leccinum. It might represent a distinct section or subsection. However, formal change of the infrageneric division of this clade should await more molecular and morphological data from additional taxa. Species to which it is phylogenetically related remain as yet unknown. Leccinum pseudoborneense X. Meng & Yan C. Li & Zhu L. Yang, sp. nov., (Figures3d–f and6 ). J. Fungi 2021, 7, 732 13 of 18

Figure 6. Microscopic features of Leccinum pseudoborneense (KUN-HKAS110156, holotype). (a) Basidiospores. (b) Basidia and pleurocystidia. (c) Pleurocystidia. (d) Cheilocystidia. (e) Pileipellis. Bars = 10 µm. Drawings by Y.-C. Li.

MycoBank: MB 838915. Diagnosis: This species differs from other species in Leccinum in its nearly glabrous and pale brown to dark brown pileus, white context in pileus lacking color change when injured, white context in stipe staining blue when bruised, initially white and then brown hymenophore not changing color when injured, white stipe covered with ochraceous to dark brown squamules, and trichodermal pileipellis composed of 3–6 µm wide interwo- ven hyphae. Holotype: CHINA. Yunnan Province: Xishuangbanna, , Bada Town, E 100◦120, N 21◦830, alt. 1900 m, associated with Castanopsis calathiformis, Castanopsis indica and Lithocarpus truncatus, 22 June 2020, G.S. Wang 947 (KUN-HKAS110156, GenBank Acc. No.: MZ412902 for ITS, MW413908 for nrLSU, MW439268 for tef1-α, and MW439261 for rpb2) J. Fungi 2021, 7, 732 14 of 18

Etymology: Latin “pseudo” = false, “borneense” = L. borneense,“pseudoborneense” is proposed because this species is similar to the species L. borneense originally described from Malaysia. Basidiomata small to medium-sized. Pileus 4–10 cm diam, subhemispherical to convex or plano-convex; surface nearly glabrous, viscid when wet, pale brown (6D6–C5) to dark brown (6F6–E5); context 5–10 mm thick in the center, white (1A1), not changing color when bruised; Hymenophore adnate to depressed around apex of stipe; white (1A1) to pallid when young and becoming brown (6B5) when mature, not changing color when injured. Tubes 4–10 mm long, creamy white (1A1) when young, and becoming brownish yellow (5C7–8) when mature, not changing color when bruised; pores fine, no more than 1 mm wide. Stipe 10–15 × 2.1–2.9 cm, clavate, always swollen downwards; surface white (1A1), covered with ochraceous (2B3–5) to dark brown (6E7) squamules, staining asymmetric blue (23E7) when injured; context white (1A1), staining blue (23E7) when injured; basal mycelium white (1A1). Basidiospores (100/5/5) (11–) 12–19 (–20) × 4–5 (–6) µm, Q = (2.75–) 3–3.58 (–3.6), Qm = 3.31 ± 0.16, subfusiform to ellipsoid, slightly thick-walled (up to 0.5 µm thick), yel- lowish brown to olive brown in KOH, yellow-brown to dark olive-brown in Melzer’s Reagent. Basidia 18–30 × 8–9 µm, clavate, 4-spored, hyaline to yellowish in KOH, yel- lowish to brownish yellow in Melzer’s Reagent. Hymenophoral trama boletoid, hyphae cylindrical, 3–6 µm wide, hyaline to yellowish in KOH, yellowish to brownish yellow in Melzer’s Reagent. Cheilo- and pleurocystidia 28–40 × 4–10 µm, abundant, subfusiform to fusiform, thin-walled, yellowish to brownish yellow in KOH, brownish to yellow-brown in Melzer’s Reagent. Pileipellis a trichoderm, composed of more or less vertically arranged 5–12 µm wide filamentous hyphae, yellowish brown to brownish in KOH, brown to dark brown in Melzer’s Reagent. Pileal trama made up of 6–12 µm wide filamentous hyphae, thin-walled, hyaline to yellowish in KOH, yellowish to yellow in Melzer’s Reagent. Clamp connections absent in all tissues. Habitat and Distribution: Scattered in tropical forests dominated by plants of the families Fagaceae (Castanopsis calathiformis, Ca. orthacantha, Ca. indica, Lithocarpus truncatus, Li. mairei and Quercus griffithii); on acidic, loamy or mossy, humid soils; moderately common in southwestern China (Yunnan Province). Additional specimens examined: CHINA. Yunnan Province: Xishuangbanna, Menghai County, Bada Township, E 100◦130, N 21◦840, alt. 1900 m, associated with Castanopsis calathiformis, Ca. indica and Lithocarpus truncatus, 22 June 2020, G.S. Wang 960 (KUN- HKAS110157, GenBank Acc. No.: MZ412903 for ITS, MW413909 for nrLSU, MW439269 for tef1-α, and MW439262 for rpb2), the same location, 22 June 2020, G.S. Wang 965 (KUN- HKAS110158, GenBank Acc. No.: MZ412904 for ITS, MW413910 for nrLSU, MW439270 for tef1-α, and MW439263 for rpb2); Nanjian County, Gonglang Town, Huangcaoping, E 100◦300, N 24◦540, alt. 1200 m, associated with Castanopsis orthacantha, Lithocarpus mairei and Quercus griffithii, 30 June 2015, K. Zhao 773 (KUN-HKAS92401, GenBank Acc. No.: MZ536632 for nrLSU, MZ543307 for tef1-α, and MZ543309 for rpb2); County, Dadugang Town, E 100◦250, N 21◦260, alt. 600 m, associated with Castanopsis indica and Lithocarpus truncatus, 30 June 2014, K. Zhao 476 (KUN-HKAS89139, GenBank Acc. No.: MZ536631 for nrLSU, MZ543306 for tef1-α, and MZ543308 for rpb2). Commentary: Leccinum pseudoborneense is characterized by the nearly glabrous and pale brown to dark brown pileus, the white context in pileus not changing color when injured, the white context in stipe staining blue when bruised, the initially white and then brown hymenophore not changing color when injured, the white stipe covered with ochraceous to dark brown squamules, and the trichodermal pileipellis composed of 3–6 µm wide interwoven hyphae. Leccinum pseudoborneense is similar to L. borneense (Corner) E. Horak, originally described from Malaysia, in that they share a brown pileus, bluish color change of the context in stipe when bruised, and similar size of basidiospores. However, L. borneense differs from L. pseudoborneense in its yellow to olive yellow hymenophore staining blue when hurt, pale yellow to yellow pileal context staining blue when hurt, and deep yellow J. Fungi 2021, 7, 732 15 of 18

context in stipe staining blue but sometimes with reddish tint at base when injured [6,84]. Leccinum pseudoborneense is phylogenetically close to L. album in our phylogenetica analyses (Figures1 and2). However, L. album has a white basidioma, white hymenophore staining indistinctly greenish blue when hurt, white context in pileus not changing color when injured, white context in stipe unchanging or only staining distinctly greenish blue at base when injured, and relatively broad basidiospores measuring 15–19 × 5–7 µm.

4. Discussion The genus Leccinum was defined and recognized variously by different mycologists. In an early molecular study, Leccinum was shown to be polyphyletic and proposed to be restricted to the sections Leccinum and Scabra by Binder and Besl [4]. Subsequently, Bresinsky and Besl [32] erected a genus Leccinellum Bresinsky & Manfr. Binder, to ac- commodate L. section Luteoscabra, including species with yellow hymenophores and/or context. In this study, the phylogenetic inferences based on the multi-locus dataset of nrLSU, tef1-α and rpb2 largely coincide with those of Binder and Besl [4], Bresinsky and Besl [32] and den Bakker et al. [33]. Thus, we adopt the treatment of Bakker et al. [33] and treat Leccinum in a strict circumscription, which only includes species of L. sect. Leccinum (Singer’s infrageneric classification with L. sect. Scabra merged to this section). Species in Leccinum are characterized by the white context lacking color changes or staining blue, gray or reddish tints when injured and the cutis-like pileipellis composed of interwoven filamentous hyphae Eleven Leccinum species with specimen citations have been reported from China before this study, of which five species (L. ambiguum, L. atrostipitatum, L. olivaceopallidum, L. potteri and L. subgranulosum) were originally described from North America, five species (L. aurantiacum, L. holopus, L. roseofractum, L. scabrum and L. versipelle) were originally described from Europe, and only one taxon (L. subleucophaeum var. minimum) was originally described from China. Our molecular phylogenetic analyses along with morphological studies identified the existence of L. quercinum, L. scabrum, L. subleucophaeum var. minimum and L. versipelle in China. The distribution of other reported species have not yet been found, based on morphological and/or molecular data. In addition, three species new to science (L. album, L. parascabrum and L. pseudoborneense) and two species new to China (L. melaneum and L. schistophilum) were revealed in our study, based on molecular and morphology evidence. In conclusion, there are nine species of Leccinum in China. Most species of Leccinum exhibit strong mycorrhizal host specificity. The host speci- ficity along with climate type and edaphic factors appear to be important factors determin- ing the distribution of different species. In China, L. melaneum, L. scabrum, L. schistophilum and L. versipelle are found in temperate forests and associated with plants of Betula platy- phylla on acidic soils. Leccinum album, L. parascabrum, L. pseudoborneense and L. subleu- cophaeum var. minimum are found in tropical forests and associated with plants of Fagaceae (Castanopsis calathiformis, Ca. hystrix, Ca. indica, Ca. orthacantha, Cyclobalanopsis glauca, Litho- carpus mairei, Li. truncatus and Quercus griffithii) and/or Pinaceae (Pinus kwangtudgensis and P. yunnanensis) on acidic soils. It is noteworthy that L. parascabrum can be found in acidic or slightly alkaline habitats. Leccinum versipelle is found in subtropical forests and is associated with plants of Populus yunnanensis on acidic soils. The combination of the color of basidioma, the morphology of pileal surface, the size of basidiospores, the morphology of stipe, the color changes when injured, the climate type, the edaphic factors and the host preferences is very important in distinguishing species in this genus.

Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/jof7090732/s1, Alignment S1: alignment of multi-locus dataset; Alignment S2: alignment of ITS dataset. Author Contributions: Conceptualization: Z.L.Y., Y.-C.L. and X.M.; field sampling: Z.L.Y., Y.-C.L., G.W. and G.-S.W.; molecular experiments and data analysis: X.M. and P.-M.W.; original draft— J. Fungi 2021, 7, 732 16 of 18

writing: X.M.; original draft—review and editing: Y.-C.L. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the National Natural Science Foundation of China (Nos. 31872618, 31750001, 32070024, 31970015), the Natural Science Foundation of Yunnan Province (2018FB027), the Ten Thousand Talents Program of Yunnan (YNWR-QNBJ-2018-125), and the Key Research Program of Frontier Sciences, CAS (QYZDY-SSW-SMC029). Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Publicly available datasets were analyzed in this study. This data can be found here: https://www.ncbi.nlm.nih.gov/; http://www.mycobank.org/; https://www. treebase.org/treebase-web/home.html, accessed on 26 August 2021. Acknowledgments: The authors thank X. H. Wang, Z. W. Ge, B. Feng and Q. Cai, Kunming Institute of Botany, CAS, for providing samples and/or related literatures. Conflicts of Interest: The authors declare no conflict of interest.

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